An aerodynamic drag reduction fairing for a generally vertical rear surface of a vehicle.
This invention relates to an aerodynamic drag reduction fairing for mounting on a rear generally vertical surface of a vehicle.
Much attention has been given to providing aerodynamic shaping of vehicles for reduction of drag. Many vehicles such as cargo trailers, campers and the like having simply at the rear end a vertical generally rectangular surface with little or no attempt to improve the drag characteristics at the rear end of the vehicle.
Much attention has been given to improving air flow characteristics at the front of the vehicle by shaping and the provision of protruding bulbous elements. The rear of the vehicle has however received little attention since the advantage to be obtained is undoubtedly less than that by shaping the front of the vehicle and in many cases the rear of the vehicle includes doors which must be accessed and therefore cannot be impeded by the addition of fairing elements.
One attempt to improve the aerodynamic drag of vehicles of this type is described in a paper presented by Kevin R. Cooper of National Aeronautical Establishment Ottawa Canada to the International Congress and Exposition Detroit Michigan Feb. 25 to Mar. 1, 1985 and entitled "THE EFFECT OF FRONT EDGE ROUNDING AND REAR EDGE SHAPING ON THE AERODYNAMIC DRAG OF BLUFF VEHICLES IN GROUND PROXIMITY".
This paper discloses in FIG. 10 the addition of panels to the rear of the vehicle. Various shapes are provided including simple plain surfaces which attach to the top and side edges of the rear of the vehicle an incline rearwardly and inwardly therefrom. This basic arrangement is modified in one example by the provision of a full tail so that the inwardly inclined surfaces taper to a vertical trailing edge at an apex spaced rearwardly from the rear surface of the vehicle. In another modification, the plain surfaces are curved.
None of the proposals achieved significant drag reductions and the paper provides no recommendation utilizing any arrangements of these types. In practice it is believed that this proposal has simply been dismissed in view of the low levels of improvement achieved and in view of the difficulties of implementing the system at the rear of the vehicle.
Other systems which are utilized at the rear of the vehicle include spoilers which are shaped to lift air at the rear of the vehicle so as to force the rear of the vehicle downwardly to improve ground friction. Other devices are used to cause air flow passing over the top surface of the vehicle to turn downwardly behind the rear surface to reduce contamination of a rear window of the vehicle. These devices do not however operate to reduce drag and are not intended for this purpose.